Wire shaving process and fixture



Patented Mar. 4, 1941 UNITED STATES.

PATENT OFFICE Caius E. Weaver, Schenectady, N. Y., assignor to GeneralElectric Company, a corporation of New York Yripplimion February 16,1939, serial No. 256,703

17 Claims.

My invention relates to a wire finishing process and device, and moreparticularlyto an improved process and fixture for shaving wire.

One object of my invention is to provide a fixture for shaving a uniformlayer of metal off the surface of a wire so as to leave a smoothunbroken surface.

For a better understanding of my invention, together with other andfurther objects thereof, reference is had to the following descriptiontaken in connection with the accompanying drawing, and its scope will bepointed out in the appended claims. v

In the accompanying drawing, Fig. 1 is a sectional elevationfthrough thecenter of my improved' fixture for carrying out my improved process;Fig. 2 is a view looking in the direction of the arrows along line 2-2;Fig. 3 is an enlarged perspective view of the wire shaving die; and Fig.4 is a front view thereof.

In the production of copper rod and wire, an ingot of the metal isrolled to the desired dimensions in a large number of successiveoperations in which the ingot passes repeatedly through the mill rolls,the distance between which is gradually decreased until the proper sizedrod is obtained. During these rolling operations, it frequently happensthat layers of scale and iron particles become embedded inthe metal,which layers of scale separate the metal, near the surface, from themain body of the rod. In the successive operations, this separated metalnear the surface is gradually lengthened and reduced in thiclmess sothat by the time the ingot has been reduced to a rod, or large sizedwire, these portions of metal become mere slivers. When rod or wire isused in electric apparatus, it is insulated and bent into variousshapes. During this bending process, the ends of the slivers,abovementioned, may become separated from the wire, and pierce theinsulation surrounding the wire. As a result, the entirecoil of suchwire may become useless.

It has also been found that when wire is drawn to very small dimensionsfrom rod received from the mills, these slivers tend to stay in the wirethrough the successive reducing stages and finally may cause breaks inthe wire. It is, therefore, of utmost importance to eliminate theseslivers from the surface of the rod received from the rolling mills.

The method most commonly used heretofore to eliminate these surfaceirregularities included pickling and open fire oxidation of the wiresurface. This method is wasteful. 'I'he black oxide formed by firing inan open furnace is practically useless and the red oxide which goes intosolution in the pickling process is also lost. The process and devicesheretofore used for mechanically removing the surface metal from the rodhave been unsuccessful and were discarded, for the reason that theywould not produce a uniform and smooth surface on the wire. It was alsoimpossible to remove continuously a uniform thickness of metal. Therehas been, therefore, a demand for a process and a fixture for carryingout such process at sumciently high speeds to produce commercialquantities of the wire. The improved fixtures built to carry out theprocess in accordance with my invention are capable of continuouslyremoving the surface of copper rod at high speed and produce a smoothsurface thereon.

The process which is the subject of my invention and which is carriedout by my improved apparatus includes as a first step a reduction of thewire area by about 10%. This step is not absolutely necessary, but whenused, makes it practicable to remove less material from the wire surfacethan is necessary to remove when the wire is in its original state. Thisreduction in cross sectional area prepares the wire for shaving and thenext operation is the actual shaving operation which may be divided intotwo steps. The first of these steps is the radial division of thesurface layer into shreds or strips of equal width, and the second stepis the separation of these strips from the wire surface. These two stepsare performed successively upon any increment of the surface layer andare performed continuously as the wire is moved through the apparatus.The division of the surface layer into a number of narrow strips reducesthe strain upon the wire surface caused by the separation of the surfacelayer from the Wire, and the equal division of the layer results in anequally distributed force being applied about the axis of the wirewhereby the wire is more easily held concentric with the cutting die.

The third step in the process is the removal of the strips from thecutting apparatus. Itis necessary, as above mentioned, to use a minimumforce in separating the strips from the wire so as to leave an unbrokensurface on the wire. If in the removal of the strips from the wire, toogreat a resistance is encountered, such surface breakage occurs. Inaccordance with my invention, the strips are permitted to slide oversmooth surfacesof a cutting die after separation from the wire in adirection radial to the wire, and

these surfaces over which the strips slide are substantially flatsurfaces. This operation reduces the resistance to removal of the stripsto a minimum and thereby substantially eliminates surface breakage.

A final step in my process is that of reducing the finished wire afterthe shaving operation. This last step hardens the newly shaved and,therefore, soft surface of the wire and protects it against abrasion orother injury during shipment and transfer to other machinery for furtheroperations.

Referring to Fig. 1 in detail, the device illustrated comprises a cradleor -pan I supported upon a suitable base I I of which only a fragment isillustrated. The pan I0 is pivoted at one end, upon a horizontal pin I2,supported in the head I3 of a vertically supported -pin I4. The otherend of the pan merely rests upon a pad I5 which is integral with thebase I0. The pin I4 projects into a hole I6 in the raised portion I1 ofthe base II and is provided with a groove I3 by means of which it islocked into the hole I6 by a pin I9. This cradle is, therefore, free torotate horizontally as well as vertically. The wire finishing mechanismis supported in this cradle upon a suitable framework bolted to the panI0 by bolts 2l.

The wire finishing mechanism includes a series of closely spaced drawingand guiding dies between which is arranged a cutting die. Thisarrangement of the dies is illustrated in detail in Fig. 1, this being across-sectional view taken through the axis of the die openings. Thefirst of this series of dies is die 25. This is the rst die throughwhich the wire is drawn. The tapered opening through the die reduces thecross-sectional area of the wire by about 10%. The length and angle oftaper in this die is governed by standard wire drawing practice. die isset into a reinforcing collar 26 and the collar in turn is supported ina holder 21 by a clamp 28. The holder is pivotally supported in the base20 by a pivot pin 29. By m'eans of this pivotal mounting this dieassembly may be moved away from the supporting structure of thesucceeding die 3|, so that this latter die may be removed from thisstructure. In operation, the die holder 21 is maintained in verticalposition by being thrust against the structure 30; more specificallyagainst the web 30. This close spacing of the drawing dies and thecutting die is desirable to prevent a catenary sag of the wire betweenthe drawing dies.

The second die in the series is the guide die 3|. The function of thisdie is to guide the Wire to the cutting die. The diameter of the holethrough this die is made slightly smaller than the diameter of the wireemerging from the drawing die 25. This produces .suicient frictionto'grip firmly the Wire and to hold it steadily while it passes to thecutting edge of the cutting die. The guide die is mounted in areenforcing shroud 32. The shroud 32 is in turn mounted in anintermediate collar 33, being held therein by a screw-collar 34. Theintermediate collar 33 is held in an adjustable collar 35 by a set screw36. By means of this collar, this guide die is laterally adjustablerelatively to the cutting die. It is necessary to provide for a slightadjustment between these two dies so as to produce a uniform thicknessof the removed metal about the axis of the wire. This relativeadjustment is preferably obtained by means of this collar on the guidedie. The same mounting collars in a supporting structure'4I.

The-

may, of course, be used for the cutting die to obtain the necessarylateral adjustment.

The adjustable collar 35, better illustrated in Fig. 2, is held in thesupporting structure 30 by four equally spaced adjusting screws 31, bymeans of which it may be adjusted laterally of the axis of the precedingdrawing die and the succeeding cutting die. This collar 35 is also heldagainst its seat in the supporting structure 30 by screws 33 which arerigidly mounted in .the supporting structure 30 and by screw caps 39which project through bores in the collar 35. These bores are ofslightly greater diameter than the screw caps 39 and thereby, permit aslight movement of the collar 35 relatively tothe supporting structure30.

Immediately following the guide die 3l, the cutting die 4I) is mountedby various intermediate The distance between the guide die and thecutting edge of the cutting die is made as short as possible so that therelatively soft wire will not be moved I laterally of the cutting dieaxis bry the cutting action. In the present apparatus this distance isonly suinciently great to permit the removed metal to iiow outwardly. Inactual practice, it has been found that one-eighth of an inch issufficient spacing for this purpose. The cutting die as illustratedenlarged in Fig. 3 is provided with a tapered front surface and atapered inner diameter. In the illustrated example, it is intended toshave or remove metal from a circular wire, but the principles hereindisclosed are applicable to bars or wire having rectangular or othercross-sections. The tapered outer surface and the tapered inner surfacemeet to form the cutting edge 42. The angles of these two surfaces areground in accordance with well established metal cutting practice andare slightly different for each metal that is cut. In th e present die athree degree taper is used for the inner surface and a 35 degree taperis used for the outer surface.

To facilitate the removal of the metal that is cut by the cutting edge,I provide auxiliary cutting edges which separate the removed metal intonarrowv shreds. These auxiliary edges are clearly illustrated in Figs. 3and 4. To provide these auxiliary cutting edges. the outer conicalsurface 42 of the die is provided, in accordance with my invention, witha series of equally spaced nat portions 43. These flat portions areground into the conical surface and are at a slightly greater angle tothe axis than the cone surface 42. These fiat portions 43 intersectahovethe cutting edge of the die, and thereby produce radial cuttingedges, or chisel edges 43 which extend radially from the circularcutting edge 42. The length of these edges is calculated to be slightlygreater than the thickness of the metal that is to be removed. Theseedges cut the metal removed from the wire radially, and therebyfacilitate a movementv of this metal in narrow strips 'over theflattened die surfaces. These flattened surfaces are preferably polishedvery smoothly, so as to reduce the friction of the removed metal againstthis surface to a minimum. It has been found in practice that reducingthis friction is important because, if this friction is too great, thesurface of the wire is torn or broken, and eventually causes breaks inthe wire when it is later drawn down to the small diameters. In theillustrated dies, six of these flattened portions are illustrated. Moremay be used. Furthermore, these need not be true flat surfaces. They maybe slightly concaved. The die 40 is supported in an intermediate collar,or collet, 44, being held therein by a screw collar 45. The intermediatecollar 44 is held in a supporting collar 46 by a set screw 41, and thecollar 46 is attached to the supporting structure 4I by screws 48.

As above described, the cutting die is provided with radial cuttingedges or chisel edges 43. These edges 43' are created by superposing,upon the conical outer surface of the cutting die, flat surfaces whichare equally spaced about the axis of the die. They are therefore at anangular relationship to each other and intersect to form the edges 43'.These flat surfaces are necessarily formed by the removal of metal fromthe conical die surface, which removal of metal results in an alterationof the circular cutting edge 42. This alteration consists of theformation of arcs between the chisel edges, each chisel edge beingaxially ahead of the center portion of each arc of the circular cuttingedge extending between the radial cutting edges. This condition isclearly shown in Fig. 3. As a result of this relationship between theradial and circular cuttingedges, every increment of the surface layer,which is to be removed, is first cut by the radial edge. Furthermore,this radial edge is necessarily at an angle to the axis so that eachincrement of the surface layer of the wire actually encounters a chiselpoint. As the wire progresses, the layer is cut radially by the radialcutting edge and is severed from the wire surface by the circularcutting edge, the complete separation of each strip, or section, of thelayer being accomplished either simultaneously or slightly subsequent tothe radial separation of the strip. The operation carried out by thecutting edge of this die can, therefore, be separated into two stepsperformed either simultaneously or successively upon each increment ofthe layer, the first of these steps being the radial separation of thelayer into strips and the second being the separation of the strips fromthe wire surface by the circular cutting edge.

After each increment of the strips is separated from the wire, it slidesover the fiat surface, between the radial edges on the die, in a radialdirection and at an angle to the axis which is determined by the flatsurface. This removal of the strips is of importance, because as abovestated in the specification, the resistance to removal must be at aminimum, otherwise, the

surface of the wire is broken. This removal ofA the strips may,therefore, be considered as a third step performed by the cutting die,and a second function of the fiat surfaces superposed upon the conicalsurface of the die.

The fourth die 50 in this assembly is another wire drawing die. Itsfunction is to harden the surface of the wire after it leaves thecutting die, and in doing this, it also may be used to reduce thecross-sectional area by about 10%. The friction on the wire at the firstdrawing die of this device produces a tension on the wire so that thesection of the wire between the two drawing dies remains straight. Ihave found that it is important to keep the wire sections, preceding andsucceeding the cutting die, perfectly straight so that the metal removedfrom the wire by the cutting die will be of uniform thickness bothlongitudinally and annularly. The drawing die 50 is supported in areenforcing shroud 5I and held in a supporting structure 52 by a clamp53. The supporting structures 4i and 52 are Connected by webs 49 whichstrengthen the combined structure and simultaneously form a container,for lubricating material, between the cutting die and the final drawingdie. Similar lubricating material containers 54 and 55 are providedbefore the guide die and the rst drawing die, respectively.

In operation, the mechanism above described may be placed between twodrums of a wire drawing machine. The wire is threaded therethrough inthe usual manner by reducing the diameter of an end of the wiresufficiently so that the wire will thread through the die withoutresistance, and is then drawn through by means of drums. The metalmostly used is copper, and

in the illustrated arrangement the stresses and' corresponding sizes ofthe dies are calculatedfor this material. When properly calculated, wiremay be drawn through this mechanism continuously at a considerablespeed, speeds up to 200 said cutting die, a guide die arranged betweenness of the material removed from the surface of the wire.

2. In a wire shaving apparatus the combination of a cutting die and adrawing die arranged in series for the passage of a wire therethrough,said drawing die being provided with a wire drawing surface for reducingthe cross-sectional area of the wire passing therethrough and placing atension upon the wire suicient to straighten it, whereby the wireentering the cutting' die is of sufficient uniformity to permit thecutting of a uniform layer of surface metal from said wire.

3. In a wire shaving apparatus the combination of an integral cuttingdie provided with a continuous annular cutting edge, a drawing diepreceding said cutting die, a guide die arranged between said drawingand cutting dies and spaced from the cutting die. by a distancesufficient only to permit free egress of the material being removed fromthe wire, and means for adjusting the axial relationship between saidguide die and the cutting die to equalize the annular thickness of thematerial removed from the surface of the wire.

4. In a wire shaving apparatus, the combination of a cutting die, adrawing'die immediately preceding said cutting die, and a second drawingdie immediately following said cutting die, said drawing dies havingdrawing surfaces arranged to reduce the diameter of the wire passingthrough them and to place a predetermined tension upon the section ofwire between them,

ting edges, said radial edges projecting from said continuous cuttingedge and having a length greater than the thickness of metal intended tobe removed by said continuous cutting edge, whereby the layer of metalremoved from a bar passing through said die is shredded.

6. A wire shaving die comprising a hollow cylinder, an inner and anouter conical surface on said cylinder, said surfaces intersecting atone end of said cylinder to form a circular cutting edge, and radialcutting edges projecting from said circular cutting edge along saidouter conical surface to shred the material cut by said circular cuttingedge.

7. A wire shaving die comprising a cylinder having inner and outerconical surfaces intersecting to form a cutting edge having a diameterequal to the diameter to which the wire is to be reduced, a plurality ofsubstantially ilattened portions upon said outer conical surface, saidflattened portions intersecting each other above the cutting edge,thereby producing radial cutting edges extending from said circularcutting edge which break the material cut from the wire into strips,said strips being removed by sliding on said ilattened portions.

8. In a wire shaving apparatus the combination of 'a cutting die, adrawing die preceding said cutting die, a second drawing die succeedingsaid cutting die and a guiding die immediately preceding the cuttingedge of said -cutting die, the diameters of said successive dies beingarranged successively to reduce the diameter of said wire by amountssuillcient to cause a tension in the sections of wire between said dieswhereby the wire is straightened and maintained ystraight while passingthrough said cutting die.

9. In a wire shaving apparatus, the combination of a cutting die, a.drawing die preceding said cutting die, and a second drawing diesucceeding said cutting die, said drawing dies being spaced from saidcutting die and from each other a suiliciently short distance to preventcatenary sag of the` wire between the dies.

10. The process of removing a layer of metal from a metallic rod whichconsists of cutting said complete layer radially into a plurality ofstri-ps and simultaneously cutting all of said strips from said rod.

11. The process of removing a layer of metal from a metallic rod whichconsists of simultaneously cutting said layer radially into a pluralityof strips and cutting each of said strips from said rod.

12. The process of removing a layer of metal 5 from a metallic rod whichconsists of cutting said layer radially into a plurality oi' stripshaving equal width Vand simultaneously cutting all of said strips fromsaid rod.

13. The process of removing an annular layer l0 of metal having aradially uniform thickness from a round metallic rod which consists ofsimultaneously cutting said layer into a plurality of equally widestrips and cutting all of said strips from said rod.

14. The process of removing a layer of metal from a round metallic rodwhich consists of cutting said layer radially into a plurality of stripsof equal width, cutting said strips from said rod and thereafterremoving said strips radially from said rod.

15. The continuous process of shaving a metal rod having a surfacecontaining defects to produce a rod having a smooth surface free fromdefects and suitable for drawing into wire which consists in passing therod through a cutting die thereby cutting the complete layer into aplurality of strips and simultaneously removing each of said strips.

16. The process of shaving a metal rod having a surface containingdefects to produce a rod having a smooth surface free from defects andsuitable for drawing into wire which consists in passing the rod througha cutting die thereby cutting from the rod an outer layer of uniformradial thickness and cuting said layer into strips before removing saidlayer from said rod.

17. The process of shaving a metal rod having a surface containingdefects to produce a rod having a smooth surface free from defects fordrawing into wire which consists in passing the rod through a cuttingdie having a series of circularly arranged arcuate cutting edges andradial cutting edges projecting from the meeting points of said arcuatecutting edges, thereby cutting from the rod a layer of substantiallyuniformradial thickness and separating the removed layer into aplurality of strips, said strips being removed radially from said rod.

CAIUS E. WEAVER.

